Tank cap for a fuel tank

ABSTRACT

In order to make available a tank cap with a sealing plug ( 13, 15; 18, 21 ) and a filler opening ( 10 ) in the fuel tank, which allows a simplified production and a more flexible use, it is proposed that the filler opening ( 10 ) is configured in such a way that the filler opening ( 10 ) allows the fixing of a sealing plug ( 13, 15; 18, 21 ) by means of two fixing systems or more.

[0001] This invention relates to a tank cap with a sealing plug and a filler opening in the fuel tank, the inner side of the filler opening having an internal screw thread.

[0002] Tanks for storing liquids such as, for example oil and fuel tanks for motor driven equipment possess a lock-up filler opening for the topping-up of liquid. Generally, the filler opening is cylindrical and configured in such a way that it can be tightly sealed with a sealing plug.

[0003] In particular, the filler opening can support an internal screw thread, for example a round thread or a trapezoid thread into which the sealing plug can be screwed with a corresponding external thread. Such a tank cap for a motor saw is known, for example, by the DE 295 19 299 U1.

[0004] Moreover, so-called bayonet caps are known such as those shown, for example, by the DE 197 00 946 A1. In bayonet caps, three inward jutting projections are typically provided on the inner wall of the filler opening which are evenly distributed on the periphery and between which there remains respectively one axially running gap. The sealing plug of a bayonet cap shows a corresponding number of radially outward jutting projections which are so placed and which are so narrow that they pass through the gaps of the projections of the filler opening when the sealing plug is axially pushed forward into the filler opening. After the projections on the sealing plug have been pushed forward axially into the tank as far as they can grip behind the projections on the filler opening, a locking action between the projections on the sealing plug and on the filler opening can be caused by an adequate turning of the sealing plug. A bayonet cap can be very quickly opened and closed since the sealing plug only has to be pushed forward into the filler opening and turned about an angle of typically 900 to 150°.

[0005] The fact that the filler opening and the sealing plug must be configured corresponding to each other is characteristic for the known thread or bayonet caps. For the production of working tools such as, for example, motor saws or the like, the production costs are thus higher if models have to be offered with both types of caps. So, it can be provided for, for example, to have a more practical bayonet cap for higher quality equipped machines and a simple cost-saving threaded cap for standard models. In order to produce an otherwise identical tank for such different models, an interchangeable insert must be provided for in the injection tool for the tank in order to be able to thus produce two tank models for the different types of caps. The expenditure of production and the costs are thus much higher. Moreover, it is disadvantageous for users of different motor equipement that they cannot simply interchange the sealing caps of the different systems.

[0006] Against this background, the aim of this invention was to make available a tank cap which allows a simplified production and a more flexible use.

[0007] This aim is reached with a tank cap with the characteristics indicated in claim 1. Advantageous configurations are contained in the subclaims.

[0008] The tank cap for a liquid tank such as, in particular, an oil or a fuel tank for motor driven equipment thus has a sealing plug as well as a filler opening of the fuel tank, projections which constitute an internal screw thread or which are at least a part thereof being placed on the inner side of the filler opening. The tank cap is characterized in that the filler opening is configured in such a way that it allows the fixing of a sealing plug with an external thread as well as the fixing of sealing plugs of other fixing types. Thus, only one embodiment of the tank with the filler opening is to realize which can be used with different caps.

[0009] According to a preferred embodiment, the tank cap is characterized in that the filler opening has a modified internal screw thread which has at least one axially running recess. Due to the fact that the internal thread of the filler opening different from a traditional thread is not configured on the circumference continuously as a helical line but that the thread spares an axially running recess, at least one sector on the cylindrical inner wall of the filler opening remains free. Because of this recess, it is possible to use the filler opening together with different sealing plugs.

[0010] For one part, the tank cap can contain a sealing plug with an external thread, the external thread being compatibel with the internal thread of the filling opener. Such a sealing plug can be screwed into the internal screw thread of the filler opening in an usual way since the interruptions of the internal screw thread which form the recess do not interfere with the function of this thread. Moreover, the tank cap can also contain a sealing plug on the cylindrical outer side of which projections are placed, the position of which on the periphery of the outer side corresponds to the position of the recesses in the internal screw thread of the filler opening. Thus, such a sealing plug is configured like the sealing plug of a bayonet cap and can be used in the manner of a bayonet cap together with the filler opening configured according to the invention. This means that this sealing plug can be pushed forward axially into the filler opening, the projections on the sealing plug moving through the recesses of the internal screw thread of the filler opening. There does not take place any combined action between the sealing plug and the internal screw thread. But if the projections on the sealing plug have been pushed forward axially into the tank so deeply that they are behind the winding of the internal screw thread, the sealing plug can be locked in the filler opening by a turn like for a bayonet cap. Here, the projections on the sealing plug cooperate with the winding of the internal screw thread in the filler opening.

[0011] Therefore, the advantage of the tank cap consists in that a single embodiment of the filler opening can cooperate with two different configurations of the sealing plug. For the production of different models of a fuel tank, the injection tool for the tank has no longer to be changed in an expensive manner but on the contrary the same tank body can be produced for all models. Thus, the difference if a threaded cap or a bayonet cap is provided for in the motor equipment only results from the type of the coordinated sealing plug (with external thread or with bayonet projections). A further advantage of the tank cap according to the invention consists in that the user of several motor driven appliances can interchange the tank caps of the appliances at will, as far as the diameter of these caps does not differ. In this way, a damaged or lost cap of an appliance being used can, for example, be temporarily replaced by the intact cap of a not required appliance.

[0012] According to a preferred embodiment of the last explained tank cap, the internal screw thread of the filler opening has two to four, preferably threee, axially running recesses distributed on the periphery. Due to the more than one recess, several projections can be adequately provided for on a sealing plug configured as a bayonet cap, these projections leading as a whole to a tighter fit of the cap. Here, the recesses are preferably evenly distributed on the periphery and have the same width. Preferably, the recesses are distributed unevenly and/or have a different width what results in the fact that a sealing cap configured correspondingly can only be inserted in a determined angular position. Such a definition can be desired in different cases for application, for example when marks, which must be orientated in a predetermined direction, are applied on the upper side of the sealing plug.

[0013] The last winding situated in axial direction to the tank inner space or the last turn of the internal screw thread of the filler opening can have another pitch than the other windings of the thread. Since the sealing plug provided with projections for constituting a bayonet cap solely cooperates with said last winding of the internal screw thread, the pitch of this thread decides with which force the cap is tightened for one turning of the sealing plug. This force can be optimally adjusted by an adequately dimensioned pitch of the last thread turn and separately from the dimensioning of the remaining internal screw thread. The last turn of the internal thread can also be placed axially spaced from the remaining internal screw thread. Due to an adequately short axial overall length of the sealing plugs with an external thread, it is ensured that by using such a thread cap the different pitch of the last thread turn cannot have a disturbing effect.

[0014] When more than one recess is provided for in the internal screw thread of the filler opening and thus more than one projection exists in the corresponding sealing plug, the upper side of the projections which is axially opposite to the tank inner space, which cooperates with the thread turn of the internal screw thread when turn-locking the bayonet cap, is preferably configured running along a helical line about the axis of the sealing plug, the pitch of the helical line corresponding to the pitch of the internal screw thread on the filler opening. Such a configuration takes into consideration the fact that, unlike in a conventional bayonet cap, the projections on the cylindrical inner wall of the filler opening do not begin at the same height but that, on the contrary, these projections are formed by the winding of the internal screw thread and thus begin at a successively rising height. This rise of the projections on the inner side of the filler opening is compensated by a correspondingly higher set-off of the projections on the sealing plug. Here, the sealing cap is preferably additionally so configured that it can be inserted into the filler opening only in a determined angular position. It is ensured in this way that each projection on the sealing plug comes to rest near the corresponding thread section of the correct axial height.

[0015] According to a further embodiment, the sealing plug shows at its end turned to the tank inner space radially telescoping legs which can grasp behind the filler opening. The effect of these legs is thus similar to that of the legs of a bayonet cap. However, since the legs are not fixed but radially telescoping, no free sparing has to be left in the filler opening for leading the legs through. Thus, the sealing plug can also be guided through a substantially cylindrical filler opening and can be fixed by radially telescoping the legs after having reached the end position.

[0016] In a further embodiment of the sealing plug, the sealing plug shows a radially expandable elastic section which can be applied under pressure to the inner wall of the filler opening, when the sealing plug is inserted. Preferably, the sealing plug is equipped with an articulated lever by means of which the first end of the sealing plug turned to the tank inner space can be pulled axially in direction of the second end of the sealing plug turned to the tank outer space, an elastic element situated between both said ends being compressed and thus radially pushed outward. Such a sealing plug can be used together with very different configured filler openings, since the elastic section is applied tightly to the inner wall of the filler opening and so bridges over shape differences. The embodiment with an articulated lever has the advantage that the sealing plug can be locked very quickly.

[0017] This invention will be explained below with reference to the figures.

[0018]FIG. 1 shows a perspective view of the filler opening of a tank.

[0019]FIG. 2 is a top view onto the tank opening according to FIG. 1.

[0020]FIG. 3 is a lateral view of a sealing plug with a thread.

[0021]FIG. 4 is a perspective view of a sealing plug with bayonet projections.

[0022]FIG. 5 shows a cross-section through an inserted sealing plug with radially telescoping legs. 8

[0023]FIG. 6 shows two cross-sections through a sealing plug with a radially expandable elastic element in the released state and in the tensed state.

[0024] A perspective view onto the substantially cylindrical filler opening 10 or on the filler neck of a tank is represented in FIG. 1. For the tank, the matter is in particular of an oil or a fuel tank of a transportable working tool such as a motor saw or the like. FIG. 2 shows the filler opening 10 in a topview. Here, three sections of a thread 11 can be recognized which are interrupted by recesses 12. The thread sections of the thread 11 and correspondingly the recesses 12 are placed uniformly distributed on the periphery, i.e. with a distance of 120°. The length of a thread section approximately corresponds to the double or triple length of a recess 12. Several thread sections can be situated aligned the one behind the other in axial direction. For many cases, it is however sufficient to provide for an unique thread section in axial direction.

[0025] In FIG. 3, a sealing plug 13 is represented in a lateral view, sealing plug on the cylindrical outer wall of which a thread 14 is provided for. Such a sealing plug can be screwed into a filler opening according to FIG. 1 and 2 in an usual way. Here, it is not important for the function of the thread that the thread 11 is interrupted by the recesses 12 on the inner wall of the filler opening.

[0026] Moreover, in FIG. 4 another sealing plug is represented for which projections or legs 17 are provided on the lower side of the cylindrical outer surface. In the perspective representation, two legs are to be recognized, a third leg is masked in the drawing. The width and distribution of the projections 17 at the periphery corresponds to the width and distribution of the recesses 12 in the thread 11 of a filler opening according to FIG. 1 and 2. Therefore, the sealing plug 15 can be inserted into the filler opening 10 like a bayonet cap by an axial forward movement. When reaching the stopper, it can be locked by a short turn, the projections 17 grasping behind the sections of the thread 11. Due to the pitch of the thread sections 11, the sealing plug 15 is inserted into the tank in axial direction. The sealing plug can then still be fixed against unscrewing by means of appropriate measures.

[0027] The upper side 16 of the projections 17 on the sealing plug 15 runs along a helical line around the sealing plug 15. Thus, the projections 17 have a different height. This is necessary because the thread sections on the inner side of the filler opening 10 also begin in different heights, this being seen axially.

[0028] The advantage of the tank cap according to the invention consists in that at least two different sealing caps 13 or 15 can be used with a tank opening 10. The thread 11 of the filler opening 10 is not only used for holding a conventional thread cap 13 but is also used additionally for fixing of bayonet cap 15. Due to the constant configuration of the filler opening 10, there are no tool interchangeable inserts, and a simplified stock keeping and a smaller number of alternatives also contribute to save costs. An advantage for the user is that he can change the sealing plugs at any time and that he can change the sealing plugs and, for example, convert from a conventional thread tank cap to the bayonet model.

[0029]FIG. 5 shows a cross-section through an alternatively configured sealing plug 18 in the inserted state. The sealing plug 18 shows at its end turned to the tank inner space radially telescoping or swing-out legs 20. In FIG. 5, these legs are represented in the extended state in which they grasp behind the filler opening and thus fix the sealing plug 15 in the filler opening. The extension and running-in of the legs 20 is carried out by a mechanism which is not represented in detail, for example by a rotation on the head of the sealing plug 18. A peripheral gasket 19 can be provided on the upper edge of the filler opening.

[0030] The advantage of the sealing cap 18 consists in that it does not require any recess for the axial leading-through of the legs 20, although such recesses do not impair its use. The sealing plug can thus be used in particular in a filler opening with an usual internal screw thread continuous on the periphery.

[0031]FIG. 6 shows a further alternative in form of a sealing plug 21. The sealing plug 21 shows at its end turned to the tank inner space a first plate 26 on which an axially running rod 23 is fixed. The rod 23 penetrates at the end of the sealing plug 21 turned to the tank outer space a second plate 24, the diameter of which is bigger than the diameter of the filler opening so that it rests outside on the edge of the filler opening. At the end of the rod 23 which projects from the second plate 24, there is a turning knuckle over which the rod is connected with an articulated lever 22. The articulated lever 22 is supported on the second plate 24 so that, for a swivelling movement of the articulated lever about 90°, the shorter leg of the articulated lever is applied between the second plate 24 and the turning knuckle and thus increases the distance of these elements with each other. As a result thereof, the first plate 26 is moved over the rod 23 in axial direction toward the second plate 24.

[0032] Furthermore, a cylindrical element 25 made of rubber is placed between the first plate 26 and the second plate 24, this element being axially upset when the distance between the plates 24 and 26 is reduced as explained above. It avoids this axial pressure radially to the side. The element 25 is then applied under pressure to the inner wall of the filler opening and thus fixes the sealing plug 21 by simultaneously sealing the tank.

[0033] The sealing plug 21 can be used together with different filler openings, in particular those with an internal thread, since the elastic section is applied to the inner wall of the filler opening and thus bridges over shape differences. The sealing plug can be locked very quickly with this articulated lever 22 by a rotation about 90°. List of reference numerals Filler opening 10 Thread 11 Recess 12 Sealing plug 13 Thread 14 Sealing plug 15 Upper side 16 Projections 17 Sealing plug 18 Gasket 19 Legs 20 Sealing plug 21 Articulated lever 22 Rod 23 Plate 24 Element 25 Plate 26 

1. A tank cap with a sealing plug (13, 15; 18, 21) and a filler opening (10) in the fuel tank, characterized in that the filler opening (10) is configured in such a way that the filler opening (10) allows the fixing of a sealing plug (13, 15; 18, 21) by means of two fixing systems or more.
 2. A tank cap according to claim 1, characterized in that the inner side of the filler opening (10) has an internal screw thread (11) and that the filler opening (10) allows the fixing of a sealing plug (13) with an external thread (14) as well as of sealing plugs (15) of other fixing types.
 3. A tank cap according to claim 2, characterized in that the filler opening (10) has an internal screw thread (11) which has at least one axially running recess (12).
 4. A tank cap according to claim 3, characterized in that the internal screw thread (11) of the filler opening (10) shows three axially runnning recesses (12) preferably evenly distributed on the periphery.
 5. A tank cap according to any of the claims 2 to 4, characterized in that the last turn of the internal screw thread (11) of the filler opening (10) axially turned to the tank inner space has another pitch than the remaining turns.
 6. A tank cap according to any of the claims 2 to 5, characterized in that the sealing plug (15) has projections (17), the position of which on the periphery of the outer side of the sealing plug corresponds to the position of the recesses (12) in the internal screw thread (11) of the filler opening (10).
 7. A tank cap according to claim 6, characterized in that the upper side (16) of the projections (17) opposite to the tank inner space runs along a helical line about the axis of the sealing plug (15), the pitch of which corresponds to the pitch of the internal screw thread (11) on the filler opening.
 8. A tank cap according to any of the claims 2 to 7, characterized in that the sealing plug (18) has at its end turned to the tank inner space radially telescoping legs (20) which can grasp behind the filler opening.
 9. A tank cap according to at least one of the claims 2 to 8, characterized in that the sealing plug (21) has a radially expandable elastic section (25) which can be applied under pressure to the inner wall of the filler opening, when the sealing plug is inserted.
 10. A tank cap according to claim 9, characterized in that the sealing plug (21) has an articulated lever (22) by means of which the first end (26) of the sealing plug turned to the tank inner space can be pushed axially in direction of the second end (24) of the sealing plug turned to the tank outer space, an elastic element (25) situated between both said ends (24, 26) being axially compressed and radially pushed outward. 